3 Week Old Chicks and New Borns

I had the good fortune of receiving 3 chicks that were a week old yesterday. The chicks, 1 barred rock, 1 light light brahma and 1 golden laced wyandotte, will be 3 weeks old when the other kids hatch.

I am presuming that I should setup another brooder for the new ones so that their older sisters don't peck at them?

thanks for the replies. since i have only one incubator and one brooder should i leave the hatchlings in the incubator w/ the unhatched eggs or should i move 'em immediately to the brooder? i was thinking i'd leave them in the brooder for an hour or two and them transfer the brooder. hopefully ChiChi, Gigi and Henrietta won't be too curious